Abomination

Regardless of the story behind the curse or condition, few abominations are willing to show the other form they can manifest. Regardless of the race they were originally, the brand or curse they obtained causes them to lose their original form and become hideous beasts. Very few people would be tolerant of such a thing, and as such most abominations tend to hide their true nature and keep moving, so as to avoid people learning what they truly are. In battle, they are strong fighters who can take multiple blows for their allies, but should the stress become too much or the pain too staggering, they may have to show their secrets to survive.

Creating an Abomination

The Abomination from Darkest Dungeon

Were they a scientist in a past life that made a mistake?
Perhaps a prisoner that was experimented on extensively, or mutated through witchcraft or magic?
Or perhaps the mark was self-inflicted or by another party member as a last-ditch effort to survive?
Either way, the abomination rarely willfully chooses to become such a thing.

Quick Build

You can make an abomination quickly by following these suggestions. First, Constitution should be your highest ability score, followed by Strength or Dexterity. Second, choose the Haunted One[1] background.

Sometimes, the most horrifying of curses may become the greatest of gifts in the face of danger...

Stress

The abomination tries to hide his affliction while he can, but in battle, under torture or interrogation the stress may start building. The more stress the abomination accumulates, the less of a grip he has on humanity. This is not necessarily a bad thing in battle, as using the stress the abomination may channel the beast or demon within to turn the tides of battle, often at the detriment of himself. The abomination's self-loathing enables him to not value his life, enabling him to protect his allies even when the blows would normally fell ordinary men.

The abomination acquires 1 stress point upon being attacked, up to the current level of the abomination. At level 3 the Abomination also gets 1 stress point whenever an ally takes any damage.

The Abomination can hold onto a number of Stress Points equal to its level.

Beast Armor

Savage Strike

At level 2, you can channel your inner beast through your attacks. If a melee or thrown weapon attack hits, you can use 2 stress points to deal 1d6 additional damage of the weapon's damage type. At level 8, an additional stress point can be used to add another 1d6 damage, and at level 14, a third stress point can be used to add a total of 3d6 damage to the weapon damage.

Eldritch Blood

Beginning at level 2, you can focus your mind on the task at hand, using your curse as a blessing to amplify all of your abilities. As a bonus action, you can use 1 stress point to gain advantage on your next attack this round.

Manifestation

At level 3, the beast can no longer be contained. When you reach your maximum stress points, you shapeshift into the manifestation you select at this level: Demon Beast, Raven Beast, Lycanthrope. You lose 2 stress points at the beginning of your turns while in your manifestation and once your stress points reach 0, you return to your original form.

Wrathful Gaze

Beginning at level 4, your inner beast can always be seen through your eyes. As an action and 3 stress points, you can force one target that is looking at you to make a Wisdom saving throw. On a failed save, the target is stunned for 1 minute. The target may make a Wisdom saving throw at the beginning of its turn each round to end this effect. You must finish a short or long rest before using this feature again.

Ability Score Increase

When you reach 4th level, and again at 8th, 12th, 16th, and 19th level, you can increase one ability score of your choice by 2, or you can increase two ability scores of your choice by 1. As normal, you can't increase an ability score above 20 using this feature.

Extra Attack

Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn. The number of attacks increases to three when you reach 10th level in this class and to four when you reach 17th level in this class.

Absolution

Starting at level 6, you learn to manipulate your cells so you can heal yourself and keep up the good fight. As an action, you chose an amount to reduce your stress points by, and gain hit points equal to twice that amount. You must finish a long rest before using this feature again.

Damnation's Gift

Starting at level 8, you are less your original race and more your manifestation at this point. When you reach 0 hit points, you can use a reaction and all of your remaining stress points to instead have a number of hit points equal to the amount of stress points used. You must finish a long rest before using this feature again.

Rain of Blood

Beginning at level 9, if you are below half your hit point max, you can use an action to use all your remaining stress points to splatter your blood all around you. All creatures within 10 ft. must pass a Dexterity saving throw or take 2d12 damage of the type specified by your manifestation (poison, necrotic, acid). You gain a number of stress points equal to the number of creatures hit. Once you reach max hit points, you can use this feature again.

Glutton for Punishment

Starting at level 12, the joy of protecting allies thrills you. When an ally within 5 ft. of you is hit by a melee attack, you can use your reaction to have the attack hit you instead.

Ageless

At level 19, the abomination gains immortality. It can't be aged normally or magically and no longer requires to eat or drink.

Inhuman Bondage

At 20th level, you use your curse to decimate your enemies. As an action, and 15 stress points, you create an aura that surrounds you for 1 minute. Enemies that start their turn within 30 ft. of you make a Wisdom saving throw. On a fail saved, they take 2d6 Psychic damage and become restrained; if they pass they take half damage and are not restrained. You must finish a long rest before using this feature again.

Manifestations

Lycanthrope

Werewolf from the D&D wiki

Feral Kind

Starting at level 3 when you select this manifestation, you gain the following features:

You grow claws that are treated as finesse and you are proficient with them. Your claws deal 1d6 slashing damage and when you are in your manifestation they deal 1d8 slashing damage. At level 5, your claws are treated as magical for the purposes of overcoming damage reduction. Your claw damage increases at level 9 to 2d6/2d8, and at level 17 to 3d6/3d8.

The damage type of the Beasts' Bile and Rain of Blood trait is acid.

Creatures restrained by your Inhuman Bondage are surrounded and attacked by ghost hounds. Ghost hounds deal 1d8 bludgeoning damage and disappear when hit. All ghost hounds disappear at the start of your turn.

Beast's Wrath

Beginning at level 7, your manifestation's traits become apart of you at all times. You have blindsight to 10 ft.

Nature's Touch

Starting at level 11, you are seamlessly in touch with your animal side. As an action, you can shapeshift into either a dire wolf, a winter wolf or a normal wolf for 1 hour. You can end this feature early as a bonus action. You must finish a short or long rest to use this feature again.

Fear

Beginning at level 13, you can gain an amount of stress points equal to your level as a bonus action. So much stress at one time is harmful on your body so you take 1d4 damage at the start of each of your turns for 1 minute. You must finish a long rest before using this feature again.

Go for the Throat

Starting at level 15, if you score a critical hit against a creature with less than half their hit point maximum, as a reaction, you can gain maximum stress points and shapeshift into your manifestation. Immediately after shapeshifting, you can use a bonus action to make a bite attack on the same creature you scored a critical hit. This attack deals 4d12 bludgeoning damage and you regain hit points equal to half the total damage dealt by this attack. You must finish a long rest before using this feature again.

Alpha Wolf

Starting at level 18, as a bonus action and 10 stress points you can coat your fangs and claws in acid for 1 minute. Whenever you deal damage with a bite or claw attack, the target must pass a Constitution saving throw or take 1d12 acid damage and become incapacitated until the end of its turn. A creature incapacitated by this feature cannot be affected so again for 24 hours but still takes acid damage on failed saving throws. You must finish a short or long rest before using this feature again.

Demon Beast

Demonic Entity

Beginning at level 3, you gain the following features when you select this manifestation:

The damage type of Rain of Blood trait is poison.

Your melee attacks deal an additional 1d6 fire damage.

At level 20, your targets hit by Inhuman Bondage must past a Dexterity saving throw or become restrained by chains that sprout from the ground. Every turn a creature begins restrained by these chains, it takes 1d8 fire damage.

you can cast summon fiend as an action each time you activate your manifestation.

Fiendish Delights

Starting at level 7, you enjoy greater delight in inflicting pain while in your manifestation. Your first melee attack each turn heals for half the damage dealt.

Summons

At level 11, you are able to summon 1d4 + 1 imps as an action. They are friendly and serve you until you dismiss them or their hit points are reduced to 0. You must finish a short or long rest before using this feature again.

Burning Aura

Starting from level 15, you have a burning aura around you while in manifestation. At the start of each your turns, you deal fire damage equal to your abomination level to each creature within 5 feet of you, and flammable objects in the aura that aren't being worn or carried are ignited. While you aren't in your manifestation, you may deal fire damage equal to your Constitution modifier to creatures within 5 feet of you at the beginning of your turn.

Sin Form

Starting from level 18, the manifestation takes the form of a deadly sin, gaining powers as apply. All attacks are considered magical for overcoming damage reduction and fiends are no longer hostile towards you.

Greed: Your greed manifests itself, turning your skin to gold and overwhelming your foes with a desire for wealth. Your Beast Armor is now 12 + Dexterity modifier + Constitution modifier, and all enemies must make a Wisdom saving throw when trying to attack you. If they fail, they turn on their allies and try to seize their riches.

Sloth: Your sloth manifests itself, slowing the movements of your foes. Your enemies are slowed as the spell on a failed Constitution saving throw while within 30 feet of you, and all Dexterity checks and attacks within 10 feet have disadvantage.

Lust: Your lust manifests itself, and you allow yourself to be consumed by desire. The air around is filled with an intoxicating aroma, forcing enemies within 30 ft to succeed on a Wisdom saving throw or be charmed for 1 minute. In addition, you may reroll a missed attack once per turn on enemies that are charmed.

Gluttony: Your gluttony manifests itself, splitting you downward and creating a hungering maw. You now have a massive mouth running vertically down your chest and stomach, which can be used to make a bite attack as an action that deals 8d6 bludgeoning damage. If the target is tiny or smaller than you and is grappled, on a successful bite, you can swallow the target. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside of you, and it takes 3d6 acid damage at the start of each of your turns. If you take 25 damage or more on a single turn from a creature inside of you, then you must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of you.

Envy: Your envy manifests, causing peasants to attack nobles and squires to turn on knights. All enemies within 30ft must succeed on a Wisdom saving throw or begin to worship you. You have advantage on Charisma and Wisdom (Insight) checks against targets that failed their saving throw.

Pride: Your pride manifests, evoking foolishness and hubris in the hearts of men. All enemies within 30ft become must pass a Wisdom saving throw or be affected by the spell confusion as they all attempt to establish who is better than each other.

Raven Beast

Mod for Darkest Dungeon by qpoljanan

Mystical Form

Beginning at level 3, you gain the following features when you select this manifestation:

The damage type of the Beasts' Bile and Rain of Blood trait is necrotic.

Creatures restrained by inhuman bondage must pass a Constitution saving throw or be blinded until the feature ends. If a creature dies while inside your inhuman bondage aura, they are risen at the beginning of your next turn as a skeleton until inhuman bondage ends.

Untapped Magic

Starting at level 7, when you are in your manifestation, any creatures you kill grant you a cantrip slot. You may cast a cantrip from any class spell list.

Master Manifesto

Starting at level 11, you can use your remaining stress points and an action to end your manifestation, dealing damage necrotic to enemies and healing allies in a 20 ft. radius equal to the number of stress points you had remaining.

Screech of Death

Beginning at level 13, you can use 5 stress points and an action to exhale in a 30ft cone. Creature must pass a Constitution saving throw or take 3d6 + 10 necrotic damage. Recharge 5-6.

Master of the Skies

Starting at level 15, ranged attacks you make while flying deal +2 damage. You can also use a bonus action to make the Dash action while you are flying.

Improved Master Manifesto

Starting at level 18, you can freely shapeshift into your manifestation regardless how many stress points you have. You do not lose stress while in your manifestation and returning to your original form when using master manifesto does not consume stress points. Additionally, you can make ranged attacks with your feathers. Each feather is treated as magical, has a range of 30 ft., and deals 1d6 damage. You may use your savage strike feature with your feather attacks as well.

Multiclassing

Prerequisites. To qualify for multiclassing into the abomination class, you must have a constitution higher than 15, and went through a harrowing event that left a damning brand.